JBox2D Circle starts moving vertically or horizontally when it collides with another Body

Question

I am trying to make ball bouncing between 4 walls using the JBox2D library in Java. The code above is the code I use to create and the ball in the world.

    // Creating the Body Definition
    BodyDef bodyDef = new BodyDef();
    // Set position to Body Definition
    bodyDef.position.set(x, y);
    // Setting body type to body definition
    bodyDef.type = bodyType;

    // Creating CircleShape object
    CircleShape circleShape = new CircleShape();
    // Setting radius to CircleShape
    circleShape.m_radius = radius;

    / /Creating Fixture Definition object
    FixtureDef fixtureDef = new FixtureDef();
    // Setting circleShape as shape of fixture definition
    fixtureDef.shape = circleShape;
    // This defines the heaviness of the body with respect to its area
    fixtureDef.density = density;
    // This defines how bodies slide when they come in contact with each other.
    // Friction value can be set between 0 and 1. Lower value means more slippery bodies.
    fixtureDef.friction = friction;
    // This define how bouncy is the body.
    // Restitution values can be set between 0 and 1.
    // Here higher value means more bouncy body.
    fixtureDef.restitution = restitution;

    // "Uploading" the ball into the world
    Body body = world.createBody(bodyDef);
    // Setting fixtureDef as body's fixture
    body.createFixture(fixtureDef);

And this is the code I used to make a wall. For example the right wall.

    // Creating the Body Definition
    BodyDef bodyDef = new BodyDef();
    // Set position to Body Definition
    bodyDef.position.set(850f, 0f);
    // Setting body type as static
    bodyDef.type = BodyType.STATIC;

    // Creating CircleShape object
    PolygonShape polygonShape = new PolygonShape();
    // Set polygon shape as a box
    polygonShape.setAsBox(1f - 44,1000);

    // Creating Fixture Definition object
    FixtureDef fixtureDef = new FixtureDef();
    // Setting circleShape as shape of fixture definition
    fixtureDef.shape = polygonShape;
    fixtureDef.friction = 0f;

    // "Uploading" the ball into the world
    Body body = world.createBody(bodyDef);
    // Setting fixtureDef as body's fixture
    body.createFixture(fixtureDef);

The ball starts to move vertically or horizontally when it collides with another body. The circle goes fine until it collides with another body. As some other posts said, I tried setting the ball's friction to 0 but that didn't work for me. These are the values I use for the ball:

tileFixture.density = 1f;
tileFixture.friction = 1f;
tileFixture.restitution = 10000f;

konmal88 konmal88 · Accepted Answer · 2018-02-14T19:40:33

I found my mistake. The problem is in the value of the restitution. The value is a lot so JBox2D makes move horizontally or vertically. I changed the value of restitution to 1f and now it works great.

JBox2D Circle starts moving vertically or horizontally when it collides with another Body

1 Answers